Compressor



Jne12,`1934.

G. LIEB El AL COMPRESSOR Filed Feb. 1, 1935 -2 Sheets-Sheet 1 Jane. 12, 1934;y

COMPRESSOR Filed Feb. 1,. 1933 -2 snets-sheet 'za4 n vf. #Fh

Patente-d June 12, 1934 UNITED STATES PATENT OFFICE COMPRESSOR Gustav Lieb, Stuttgart, and Hermann Meier, L'inSlnd/Unterturkheim, Germany, assignorsA y to Robert Bosch Aktiengesellschaft, Stuttgart, Germany Application February 1, 1933, .S'erial No. 654,718 In Germany February 9, 1932 4 Claims. (Cl. 23o-24K) The present invention relates to compressors, are shown in the accompanying drawings, in the suction space or chamber of which is conwhichinected to the pressure space by a pipe or duct, Figure 1 is an axial section on the line 1-3-1 the inlet to which is controlled by a pressureof Fig. 2 through an eccentric piston rotary controlled member, which opens the pressure compressor adapted more especially for small re- G0 equalization pipe on the stoppage of the comfrigerating machines. pressor, so that the pressure on both sides of the Figurev 2 is a top plan view of the compressor, piston is equalized, whilst it closes as soon as with the upper bearing cover removed. the driving motor of the compressor has attained Figure 3 is a partial section on the line 1-3-3 a certain speed. The equalization of pressure on of Fig. 2. f

both sides of the piston facilitates the starting, Figure 4 a section through a second' form of so that a less powerful and therefore smaller moconstruction taken on the line 4-4 of Figure 5, tor can be employed than if the compressor had which is a top plan view, with the upper bearing to start against the excess pressure prevailing on Cover removed. 16 its pressure side, that is, under full load. It is Figure 6 is aseoton on the line 6-6 0f Figure '0 already known to operate the valve controlling 4, and l y the equalization of pressure between the suction Figure 7 a further cross-section on the line and the pressure spaces of the compressor by 7--7 of Fig. 4. means of a current of ypressure gas produced by Referring to the example of the construction the compressor, the current of pressure gas beingv Shown in Figs. 1-3 inclusive, the casing of the 1B controlled in its turn by an auxiliary valve which compressor cOnSiStS 0f a Cylindrical Wall 10'whioh is brought into operation under the action of is closed at the two endsby bearing covers 11, 12, oil pressure produced by a lubricating oil pump by'meanS 0f Which it' iS reVOlubly mounted 011 connected with the compressor when the comthe stationary shaft 13. The casingv 10 is driven presser is running. It is also known to control preferably by an electric motor, into the arma- B0 `the valve controlling the pressure-equalization ture 1401 Which it iS bililit In the casing 10 iS pipe by a. piston which is moved by the pressure located the piston 15, which is mounted loosely in the lubricating oil pipe after a valve operated 0n an eccentric 16 fixedly connected with the by the centrifugal acceleration of the starting Stationery'shaft 13, and which contains an inlet compressor has closed anopen outlet of the lubripassage 17. ,and cn Outlet passage 18. By Ithe 88 eating oil pipe when the compressor is stopped. eccentric positioning of the piston 15 a crescent- .In contradistinction to these known relief de- Shaped Working `chamber results between its vices, the present inventionl consists in that a periphery end the inner Wall 0f the casing, which controuing member is provided in the pressureis divided into a suction space 22 and a pressure equalization pipe or duct between the suction and Space 23 by an abutment 21 guided in the piston 00 the compressor spaces of the compressor, which 15.2nd DiVOtally connected by rotary DinS 19, 20 is directly influenced by the pressure in the lubrl- With the bearing COVBIS 11, 12. The medium to Aeating oil pipe (that isto say, without the interbe compressed ows into the suction space 22 mediary of pressure gas pipes, auxiliary valves through a passage 24 in the stationary shaft 1-3 or the like), and opens the pressure-equalization and the inlet passage 17 in the piston whilst 06. pipe as soon as the lubricating oil pressure falls thevcompressed medium Can escape through the owing to the stoppage of the compressor and the Outlet Passage 18 in the DStOn and an outlet lubricating oil pump, whilst it closes the pressurepipe 25 DIOVded in the hollow shaft 13. The equalization pipe as soon as the pressure in the piston 15 iS pivctally Connected With the rotary lubricating oil pipe has attained a definite value. casing 10 by the abutment 21, the outer rounded 100 Premi-amy, the pressure-equalization pipe and end of which engages with a tight joint in a corthe member controlling it are arranged in a conresponding lrecess in the easing wall 10. The structional part which separates the pressure abutment can thereby oscillate on'the pins 19 space from the suction space or chamber (in roand 20 corresponding to the eccentric movement V tary piston compressors preferably in the abutof the rolling piston 15 in the compressor casing, 105 ment) so that the dimensions of the compressor these pins being fastened in the bearing covers may be kept small, an advantage which is par- 11, 12 and bi'cecting intO 9 passage 26 traversing tlcularly important for small rrefrigerating ma-A the abutment 21. A connecting duct (pressurechines, equalization duct) is provided between the suc- Two examples of construction of the invention tion space 22 and the pressure space 23 separated 110 from it by the abutment 21. This pressureequalization duct is formed in the case of Figures 1 to 3 by a groove 27 starting from the suction space 22 and formed in the end'face of the compressor casing 10, which groove opens into a passage 28 traversing the compressor casing and running parallel to the axis of rotation of the compressor, and an opening or a short passage 29 leading from the passage 28 into the pressure space 23. The passage 29 is controlled by a piston valve 30, provided in the passage 28; This controlling member stands under the influence of at least one loading spring 31, which 'is supported at one end on the bottom of the'hollow piston valve 30 and at the other end in a recess in the bearing cover 11. The spring has a tendency to press the controlling member away from the passage 29 and thus to keep open the passage through the pressure-equalization 'duct 27, 28, 29. 'I'he piston valve 30 is moved against the action of the spring 31 into the closing position by a suitable pressure medium e. g. oil under pressure, which is supplied from below through a passage 33 provided in the bearing cover 12 and 'its bush 32 by a conveying device which is dependent on the drive of the compressor. For this purpose, the part of the stationary shaft 13 situated in the bush 32 of the bearing cover 12 is provided with helical threads 34, which form a conveyor worm for the pressure oil.v The pressure oil is preferably taken from an oil sump 35 surrounding the shaft 13. kIt enters at 36 into 'an annular space 37, which is connected by cross ducts 38 cut in the lower end of the bush 32 of the bearing cover 12 (Figure 7) to a second annular space 39 into which they conveyor worm 34 dips. As soon as the conveyor casing 10 revolves, a like motion is imparted to the bushing 32 by reason of the fact that it is fxedly secured to the bottom plate 12 of the rotary casing or cylinder element of the compressor and oil is conveyed upwards by the screw-threads 34 due to the revolution of the bushing about the stationary screw threads. A part of the oil serves for lubricating the rolling piston. 15, whilstl a further part is compressed into the passage 33 below the bottom of the controlling member 30. Only after the compressor has been started for Aa certain time does the pressure ofthe liquid acting on the controlling member 30 become so great that it is able to overcome the force of the spring -31. `As soon as this takes place, the piston valve 30 is moved upwards until it covers the opening 29, so that the free passage of the pressureequalization duct 27, 2829 is closed. The compressor only becomes effective in this position of the controlling member 30. The retractive force of the spring 31 and the quantity of oil conveyed by the -oil pump 34 are so proportioned that the controlling member 30 only closes the pressureequalization duct when the driving motor of the compressor has attained its full speed. possible by this means to employ a motor having a small starting torque and correspondingly small dimensions.

The construction shown in Figures 4 and 5 differs from that just described only by thefact that the controlling member 30 is arranged in the passage 26 of the abutment 21 for the pins 19, 20, whereby the construction is simpler and cheaper because a special recess for the controlling member 30 is dispensed'with. The piston valve 30 moves in the free space in the passage 26 situated between the ends of the rotary pins 19, 20whereby it controls a cross hole 40 which It is connects this space with the'pressure space 23. 41 is a second cross hole, whichconnects the space between the two pins 19, 20 with the sucl tion space 22, and preferably has such a position in regard to the controllingmember 30 that it remains permanently open. During the stoppage and the starting of the driving motor the piston valve 30 is pressed downwards by the loading spring 31 acting upon it, so that the passage 40, 26, 41 from the suction space to the pressure space is free, and the same pressure prevails in lthese two spaces. The piston valve 30 is also operated as in the rst described construction by pressure oil, which isconveyed by the viscosity pump already described, and penetrates through the hollow pin 20 below the bottom of the piston valve 30. The other pin 19, which also is partly hollow, serves for receiving one end of the loading spring 31. Themode of action of this second construction is the same as in the first one.

The second construction is, however, to be preferred to the rst, because a speciall recess rfor the arrangement of the controlling member 30 isv dispensed with, and because, furthermore, the pressure-equalization between the suction and the pressure spaces` of the compressor can rbe established by two simple cross holes 40, 41, which open into the passage 26 in the abutment 21 for the pins 19, 20.

The invention is, for the sake of simplicity, illustrated only in connection with a rolling piston or rotary abutment compressor. Itv may however also be employed in other compressors.

We declare that what we claim is:

1. A rotary compressor comprising a casing, an eccentric piston and an abutment engaging in a slot in the piston to form a suction space and a pressure space in the casing, said abutment having a pressure equalizing duct formed therein between the suction space and the pressure space and a controlling member in said duct,

.lubricating oil supplying means lfor said compressor, and oil conduit means subjecting said `controlling member tol the oil supplyv pressure whereby said controlling member is influenced directly by the pressure of the lubricating oil of the compressor and adapted to close said duct aftervthe compressor has been started up and when the lubricating oi=1 pressure has reached a given value.

2. A rotary compressor comprising a casing, an eccentric piston and an abutment engaging in a slot in the piston to form a suction space and a pressure space between thev casing land piston, said abutment having a guide pin passage therein, guide pins engaging in said casing and in said opening in the abutment for pivoting the abutment to the casing, said abutment also having ports extending from said passage to the suction and pressurel spaces to form with said passage an equalizing duct between the 'suction and pressure spaces, and a piston movable' in said passage to open and close one of said ports to isolate the suction and pressure spaces, lubricating oil supply means for said compressor producing an oil supply pressure varying directly with the rotational speed of sa-id compressor and oil conduit means subjecting ysaid piston to the oil -supply pressure wherebysaid piston is influenced directly by the pressure of the lubricating oil of the compressor. Y

3. A rotary compressor comprising a casing, an

eccentric piston and an oscillatable abutment engaging in a slot in the piston and pivoted to the casing to form a suction space and a pressure space in the casing, said abutment having a pressure equalizing duct formed therein coaxial with the axis of oscillation of the abutment adapted to connect the suction space with the pressure spaeg-'and a controlling member in said duct, lubricating oil supplying means for said compressor producing an oil supply pressure varying directly with the rotational speed of said compressor, and oil conduit means subjecting said controlling member to the oil supply pressure whereby said controlling member is influenced directly by the pressure of the lubricating oil of the compressor and adapted to close said duct after the compressor has been started up and when the lubricating oil pressure has reached a given value.

4. A rotary compressor comprising a cylinder element open at its opposite ends, coversdetachably secured to said opposite ends of said cylinder element, an eccentric piston in said cylinder element, an oscillatable abutment element engaging in a slot in the piston and pivotally journaled ina side wall of said cylinder element to form a suction space and a compression space in the chamber formed by said cylinder element, said piston and said covers, one of said elements having a bore through its wall from end to end parallel with the rotational axis of the compressor and ducts in its wall connecting said bore on opposite sides of said abutment element with said suction and compression spaces,v a piston valve slidably movable in said bore to open and close one of said ducts, said piston valve hav-v ing a loading means tending to move said valve to position uncovering said one duct, lubricating oil supply means for said compressor producing an oil supply pressure varying directly with the rotational speed of said compressor and oil conduit means connecting said oil supply means with said bore on the side of said piston valve effective in moving said valve to position closing said one duct whereby said piston valve is influenced directly by the pressure of the lubricating oil of the compressor to close said one duct after the compressor has been started and upon .the lubricating oil pressure reaching a given value.

GUSTAV LIEB. HERMANN MEIER. 

